Device for preparing a copy by means of latent electrostatic images



March 19, 1963 w. LIMBERGER 3,031,677

nsvzcr: FOR PREPARING A COPY BY MEANS OF LATENT ELECTROSTATICTIMAGES" Original Filed Oct. 22, 1957 4 f 4 0 oo- 9Y8 Walter Limberger INVENTOR.

BY 96" g AGENT.

United States Patent P 3 9 Claims. (Cl. 951.7)

My present invention relates to an apparatus for making prints from a master copy by a xerographic process.

It is known to duplicate a master copy on a flexible sheet by placing the sheet in contact with a second sheet, bearing an electrostatically charged xerographic layer, and illuminating the two sheets so as to form a latent electrostatic copy of the master on the xerographic layer; the latent image can then be developed by dusting the exposed xerographic layer with a toner and fixing the toner particles onto the layer by a fusion process. My present invention has for its object the provision of an improved and conveniently operabledeviceof this character which, in a preferred embodiment, can be designed I here in such manner ,as to leave a portion of the guide path exposed between these chambers whereby the master copy can be conveniently separated from the xerographic layer and removed immediately after the latter has been exposed. In order to prevent any undesired entrainment of the xerographic layer by the master copy, I provide suitable retaining means such as, for example, asuction device at the exposed guide-path portion to hold the layer-bearing sheet in place.

, In an advantageous embodiment, the developing chamber which follows the exposed portion of the guide path contains a magnetic array adapted to distribute the toner particles over the layer surface in a manner more fully disclosed and broadly claimed in my co-pending application .Ser. No. 691,691, filed October 22, 1957, of which the present application is a division;

Further advantages and features of the invention wil appear from the following description of an embodiment which is illustrated in the accompanying drawing.

In the drawing: 1

FIG; l shows'a side view of to the invention in section;

.FIG. 2 shows a plan view of. part'of the apparatus according to FIG. 1; and

FIG. 3 shows a side view of the part of. the apparatus illustrated in FIG. 2.

the apparatus according V and the master. The plate 55 extends into the housing 3,081,677 Patented Mar. 19, 1963 "ice master copy. This master copy consists for example of opaque paper. The apparatus is'suitable also for master copies of normal paper, which are light-permeable and carry an image only on one side.

' The" forming device 44 is arranged at the upper side of the slot 42 for the layer support and, in the embodiment illustrated, comprises three wire-shaped electrodes. It is possible to provide'a contact chargewith these electrodes which press the paper onto thelower limiting surface of the guide slot 42, the latter surface being constructed in the region of the forming device as the counterelectrode. The electrical parts of the apparatus are not shown in the embodiment illustrated, since they are not essential to a comprehension of the present invention.

At the guide surfaces forming the slots 42, 43 there is mounted the illuminating device 39 which consists essentially of a glass plate 45 with a window 52 in the guide path for the layer support, a pressure and feed 50 which terminates behind the roller 46 ina steeply inclined wall. This wall extends to the guide path for the layer support and merely leaves a s1ot.51 .above a supporting plate for the passage of the layerf support extension 53 for the developing device and is perforated at least in the section-between the housing extensions 50 and 53. The apertures 54 forming the perforationsare arranged obliquely, so that the upper ends of the apertures are inclined opposite to the direction of advance of the layer support. These perforations cooperate with an air aspiratorarranged in the lower part of the apparatus, for example the suction side of a blower, so that the layer support is held down by the partial vacuum prevailing in the apertures 54 of the plate 55. This guiding of the layer support on the plate 55 does not act on the master copylying above the layer support, which can therefore be readily removed from the intermediate space between the housing extensions 50 and 53. Automatically operating devices may, of course, be provided for the separ-ation of the layer support and the master copy. There is also the possibility of at least partly covering the section between the extensions 50 and 53'. Preferably, the separation of the layer support and the master copy. occurs at an. edge 56 constructed especially for this purpose on the inclined forward wall 57 of the extension53,so that the The apparatus illustrated in the drawing consists of 55 a lower part 35 divided essentially into-three chambers 36, 37 and 3,8, which are separated from one anotherby verticalpartitions. .The guide path for the layer support is, arranged at the upper-surface of the lower part 35 of the housing. The division of the lower part 35 of the housing into three chambers 36, 37 and 38 corresponds .toa separation of the apparatus essentially int-oan illuminating device 39, a developer device 40 and a fusing device 41. Extensions 50, 53- are provided on theupper side of the housing and surround the/parts of the apparatus lying above the guide pathfor the layer,

layer support provided with the latent electrostatic image iscovered during its passage through the intermediate space between the extensions 50 and 53.

Within the housing extension 53, which is located over thelch'amber 37 of the lower part of the apparatus, a pair of feed rollers 58 are provided which are resiliently urged towards each other and are driven according to the arrows 5-9. The rollers preferably have a rubber covering on their surfaces for lighthandling of the layer support. The distance between the pressure roller 46 and the pair of feed rollers 58 is smaller than the length of the copies normally to be prepared, so that the forward edge of the layer support is gripped by the pair of rollers ,58 before the layersupport is released by the pressure roller '46. j

"Behind the pair of feed rollers 58, the guide path for the layer support consists of a plate 60 over which the developing device 40 is located. This developing device is also represented in different views illustrated in FIGS. 2

and 3.

, conveyor belt, which consists of rubber.

FIG. 3.

It consists of an endless conveyor belt 61 on which mutually parallel bar magnets 62 are so arranged that like poles face the layer support passing over the plate 60. The magnets are, for example, vulcanised on to the The conveyor belt 61 is guided on drums 64, 65 arranged above and laterally of the layer support 63; for example, the conveyor belt 61 may be provided at the side facing the drums with projections which engage grooves in the drums, or vice versa. Special arrangements are provided for preventing downward slipping of the conveyor belt, such as for example, edge strips 66 perpendicular to the direction of the magnets. These edge strips 66 engage in corresponding apertures formed at the upper end of the drum and serve to guide the belt.

The drums 64, 65 are mounted above the plate 60 in a horizontal partition 67. The shaft of at least one drum is passed through the partition 67 and is coupled, if re quired over a reduction gear, with the driving motor 68. This arrangement'is readily appreciable particularly in It can also be seen from this figure that the driving motor 68 is arranged only above the drum 64, the drum 65 being freely mounted in the partition 67.

Positioned laterally of the partition 67 in the housing extension 53 are upwardly open partition containers 69, 70 which serve as supply containers for the developer. The supply containers 69 and 70 are funnel-shaped at their lower sides and are provided at this lowest point with a supply opening in which distributing rollers 71, 72 are located. The distributing rollers can be driven with different rotative speeds so that the amount of developer respec tively dispensed from the containers 69 and 70 can be individually controlled. Beneath the rollers 71, 72 are chutes 73, 74 which direct the developer particles supplied by the containers to the lower poles of the operating magnets 62. In the region of the chutes 73, 74, several directing magnets 75, 76 are so positioned that unlike poles of the operating magnets 62 and of the directing magnets 75, 76 face one another. In particular, the directing magnets are so arranged that they are inclined to the axes of the adjacent operating magnets so that the magnetic field located under the lower poles of the operating magnets is increased. The magnets 75, 76 have the purpose of direoting toward the poles of the operating magnets the brush-shaped bundles or tufts of developer particles, which were deformed in wiping over the layer support 63, before these tufts are again guided over the layer support 63 as a result of the rotation of the conveyor belt 61. The arrangement of the directing magnets 75, 76 in connection with the powder-distributing device also has the advantage that at the same time tufts of particles are formed on the poles of the directing magnets facing the operating magnets, these stationary tufts preferably coming into direct contact with the moving tufts on the operating magnets. An intensive transfer of fresh, i.e. unused, developer is thus ensured. ,7

After the bundles are formed once on the operating magnets 62 and the directing magnets 75, 76, it is sufficient merely to supply toner which is added to the bundles from the carrier particles of the developer. Preferably, in order to augment the number of carrier particles released during the wiping of the photo-electric layer, a developer strongly enriched with toner is supplied from the containers 69, 70.

In one embodiment of the invention, the operating magnets 62 and the directing magnets 75, 76 are made of equal strength and the developer is directed by the chutes 73, 74 approximately in the middle between facing poles of the operating and directing magnets. There is also the possibility, in a modified construction, of making the directing magnets 75, 76 somewhat weaker than the operating magnet 62 or arranging the chutes 73, 74 sothat the developer is guided nearer to the poles of the operating magnets than to those of the directing magnets.

In the chamber 37 of the lower part of the apparatus,

which is located beneath the extension 53, a container 77 is removably arranged to receive released developer particles which fall from the layer support at the sides thereof or fall from the poles of thedirecting magnets. The developer particles collected in this container can be returned to the supply containers 69, 70 after having been enriched, if required, by the addition of toner.

The fixing device is located behind the extension 53 on the upper side of the apparatus. This device consists essentially of heating elements for fusing in the toner which is applied to the contours of the electrostatic image. Infra-red emitters 78 are arranged above the photo-electric layer, over which reflectors 79 are disposed which direct the upwardly passing heat rays to the layer support. In the region of the fixing device, the guidepath for the layer support consists of a plate 80 in which heating elements 81 are arranged. These heating elements cause heating of the layer support from the back. Furthermore, the plate 80 is interrupted by apertures 82 through which, as with the apertures 54, a partial vacuum is applied to the back of the layer support in order to draw it onto the plate 80. Furthermore, this partial vacuum acting through the apertures 82 has the object of extracting from the fixing device the fumes which arise in fusing in the toner. These fumes would impair the operation of the apparatus if they were distributed through the whole unit.

At a suitable location, for example, at one, side wall of the lower part 35, a blower 89 is included whose suction side is connected with a pipe 88 to produce the aforementioned partial vacuum. The openings 86, '87 of this pipe 88 lie beneath the openings 54 in the plate 55 and the openings 82 in the plate 80.

The fixing device 41 is provided with a pin roller 83,

at the exit side for the copies, which is driven in the direction of the arrow 84. This pin roller extends over the whole width of the exit slot and therefore also forms a cover for this exit slot and constitutes a feeding device which does not disadvantageously affect the prepared copies because of the arrangement of pins on the circumference of the roller. prepared copies over a support platform which is arranged at the back of the apparatus, preferably on the lower part 35.

What I claim is:

1. An apparatus for duplicating a master copy, carried of said developing device, said enclosures being. spaced apart by an exposed portion of said path of sufiieient length to enable the gripping of a sheet from above, said 7 first enclosure being provided with a slotted portion forming an inlet adjacent one extremity of said path for. the

admission of both said sheets into said housing, said first enclosure further having a rear wall spaced above said supporting means sufiiciently to form a firstclearance for the emergence of both said sheets onto said exposed por-- tion whereby said first sheet, on being properly positioned atop said second sheet, may be removed from the latter, said second enclosure having a front wall with a lower sheet-separating edge turned toward said first clearance and spaced above said supporting means sufficiently to form a second clearance for the reintroduction of said second sheet into said housingwhile said first sheet isdefiected upwardly along said second enclosure by said edge,

said second enclosure being further provided with an exit slot adjacent the opposite extremity of said path for the This feed roller 83 advances the discharge of said second sheet after movement of the latter past said developing device; first feed means ahead of said exposed portion for advancing both said sheets past said illuminating device; second feed means beyond said exposed portion for advancing said second sheet past said developing device; and retaining means at said exposed portion for holding said second sheet in contact with said supporting means during removal of said first sheet.

2. An apparatus according to claim 1 wherein said developing device comprises distributing means for fusible toner particles in said second enclosure, further including a fixing device comprising heating means for fusing said particles onto the photoconductive layer, said fixing device being positioned beyond said distributing means along said path, said retaining means comprising a first apertured plate forming part of said supporting means at said exposed portion, said supporting means including a second apertured plate underneath said heating means, further comprising suctionmeans in said lower portion operatively connected with the aperture of both said plates for holding down said second sheet on its passage over said plates.

3. An apparatus according to claim 2 wherein said lower pontion is provided with partition means dividing it into a first chamber underneath said first enclosure and said exposed portion, a second chamber underneath said distributor means, and a third chamber underneath said heating means, said suction means comprising a source of low pressure having outlets in said first and third chambers, said second chamber being provided with receiving means for excess toner particles.

4. An apparatus according to claim 1 wherein said supporting means comprises a plate having apertures at the location of said exposed portion, said retaining means comprising a suction device operatively connected with said apertures.

5. An apparatus according to claim 4 wherein said apertures have axes enclosing with the surface of said plate an acute angle pointing in the direction of advance of said sheets.

6. An apparatus according to claim 1 wherein said supporting means is provided with a gap underneath said second enclosure, said second feed means comprising a pair of cooperating transport rollers positioned in said path at said gap.

7. vAn apparatus according to claim 1 wherein said sheet-supporting means is provided with a straight pathforming surface in a substantially horizontal plane, said surface extending from said first clearance beyond said exit slot.

8. An apparatus for duplicating a master copy, carried on a first flexible sheet, on a second flexible sheet provided with a photoconductive layer, comprising stationary guide means establishing a guide path for said sheets; first housing means below said guide path, said guide means being provided with a window in the vicinity of said first housing means; illuminating means in said first housing means for forming a latent image of said master copy in said layer; second housing means above said guide path provided with a slotted portion adjacent one extremity of said guide means forming an inlet for said sheets; first feed means in said second housing means for displacing said sheets along said path past said window, said second housing means being provided with an outlet slot for said sheets opposite said slotted portion; third housing means above said guide means and spaced from said second housing means along said path, said third housing means being provided with an entrance slot for said second sheet aligned with the outlet slot of said second housing means, a sheet-separating edge overlying said entrance slot and turned toward said outlet slot and an exit slot for said second sheet opposite said entrance slot while said first sheet is deflected upwardly along said (third housing means by said edge; developing means within said third housing means for rendering visible the image carried by said second sheet; heating means beyond said developing means within said third housing means for fusing said particles onto the photoconductive layer, and retaining means on said guide means between'said second and third housing means for holding said second sheet against said guide means whereby said first sheet, afiter being passed through said second housing disposed above said second sheet, may be manually stripped therefrom in the gap between said second and third housing means while said second sheet is further displaced through said third housing means upon upward deflection by said edge.

9. An apparatus according to claim 8 wherein said guide means is provided with a straight path-forming surface in a substantially horizontal plane, said surface extending from said outlet to the region of said heating means.

References Cited in the file of this patent UNITED STATES PATENTS 2,357,809 Carlson Sept. 12, 1944 2,551,582 Carlson May 8, 1951 2,589,748 Trump Mar. 18, 1952 2,735,346 Frantz Feb. 21, 1956 2,811,088 Walker Oct. 29, 1957 2,826,168 Grant Mar. 11, 1958 2,841,461 Gleason July 1, 1958 2,854,947 Giaimo Oct. 7, 1958 2,878,742 Trump Mar. 24, 1959 2,887,942 Frantz May 26, 1959 2,918,858 Dieterle Dec. 29, 1959 

1. AN APPARATUS FOR DUPLICATING A MASTER COPY, CARRIED ON A FIRST FLEXIBLE SHEET, ON A SECOND FLEXIBLE SHEET PROVIDED WITH A PHOTOCONDUCTIVE LAYER, COMPRISING STATIONARY SHEETSUPPORTING MEANS ESTABLISHING A TRANSPORT PATH FOR SAID SHEETS; AN ILLUMINATING DEVICE FOR FORMING A LATENT IMAGE OF SAID MASTER COPY IN SAID LAYER AND A DEVELOPING DEVICE FOR RENDERING SAID IMAGE VISIBLE SUCCESSIVELY POSITIONED ALONG SAID TRANSPORT PATH; A HOUSING SURROUNDING BOTH SAID DEVICES, SAID HOUSING HAVING A LOWER PORTION BELOW SAID PATH AND AN UPPER PORTION ABOVE SAID PATH, SAID UPPER PORTION FORMING A FIRST ENCLOSURE IN THE REGION OF SAID ILLUMINATING DEVICE AND A SECOND ENCLOSURE IN THE REGION OF SAID DEVELOPING DEVICE, SAID ENCLOSURES BEING SPACED APART BY AN EXPOSED PORTION OF SAID PATH OF SUFFICIENT LENGTH TO ENABLE THE GRIPPING OF A SHEET FROM ABOVE, SAID FIRST ENCLOSURE BEING PROVIDED WITH A SLOTTED PORTION FORMING AN INLET ADJACENT ONE EXTREMITY OF SAID PATH FOR THE ADMISSION OF BOTH SAID SHEETS INTO SAID HOUSING, SAID FIRST ENCLOSURE FURTHER HAVING A REAR WALL SPACED ABOVE SAID SUPPORTING MEANS SUFFICIENTLY TO FORM A FIRST CLEARANCE FOR THE EMERGENCE OF BOTH SAID SHEETS ONTO SAID EXPOSED PORTION WHEREBY SAID FIRST SHEET, ON BEING PROPERLY POSITIONED 